Strainer for coffee makers



p 1953 F. w. STORNER STRAINER FOR COFFEE MAKERS 2 Sheets-Sheet 1 Filed Sept. 9, 1948 INVENTOR.

Filed Sept. 9, 1948 p 29, 1953 F. w. STORNER 2,653,717

STRAINER FOR COFFEE MAKERS 2 Sheets-Sheet 2 INVENTOR.

Patented Sept. 29, 1953 UNITED STATES PATENT OFFICE 7 Claims.

My invention relates generally to a strainer or filter and more particularly to a strainer or filter for a coffee makeror the like.

A popular form of codes maker presently being marketed and used comprises two vessels or receptacles, the lower one of which has a restricted pouring throat or neck and may serve as a coffee urn or flagon, the upper one of Which has a large upper opening or throat and a downwardly extending spout or funnel which is adapted to be positioned in airtight relation in the throat of the lower vessel. Usually a gasket is employed. between the outer wall of the spout of the upper vessel and the throat of the lower vessel to maintain, an airtight junction, said gasket ordinarily being carried at the uppermost end of the spout. The spout or funnel extends downwardly into the lower vessel with its lowermost end being positioned slightly above, the bottom wall of the lower vessel. A strainer or filter is generally disposed in the upper vessel at the entrance to, the spout or funnel. and some means is usuallyemployed for retaining the strainer in position.

In use, such coffee maker has a quantity of water placed in the lower vessel corresponding to the amount of coffe which is desired whereupon the spout of the upper vessel is inserted into the lower vessel and an airtight junction is formed in the neck of the lower flask about the spout. At

this time the spout extends down into the water 0 in the lower vessel, In the, upper vessel a quantity of ground coffee is disposed around or on, top of the strainer or filter, the quantity used being gov- 'erned by the amount of coffee which is to be wardly through the spout and through the strainer or filter into the upper vessel where the hot water mixes with the groundv coffee, with. a resultin coffee infusion. The. water continues to be delivered through the spoutinto the upper vessel until such time as the. amount of water in the lower vessel is insufiicient to cover the lower end of the spout. At that time continued boiling merely results in. the release of water vapor through the spout and up through the coifee infusion in the upper vessel. It is customary at such time. to remove the coffee maker from the source of heat, whereupon the cooling of the flask and the. vapor therein causes. a contraction of the vapor and aresulting vacuum. The. coffee inthe upper vessel then, flows back to. the lower vessel through the strainer and spout. The strainer acts. to strain out. coffee grounds and to permit the passage of the liquid. When all of the liquid has returned to the lower vessel the upper one is removed and the lower one isused as a coffee urn or fiagon,,if it has, ahandle.

In devices of this type the strainers or filters have been a source of annoyance and dissatisfaction both because of their tendency to let coffee grounds pass intothe lower vessel and also because of their, tendency to clog, with the result that the coffee infusion fails to flow into the lower vessel. Removal of the strainer or filter to eliminate the clogging would, at such time, permit coffee grounds to flow into the lower vessel, an occurrence whichwould be highly unsatisfactory. To my knowledge none of the currently used types of. filters consistently gives satisfactory results and it is a primary object of my invention to pro- Vide, a strainer or filter which will uniformly provide satisfactory straining of the grounds from the coffee infusion without clogging,

One of the advantages of the strainer of my invention is that when the coffee grounds tend to clog the strainer, the strainer automatically eliminates the clogging action without any attention by the user. The construction of the strainer of my invention is such that when it tends to become clog ed from coffee grounds blocking the passageways which it defines between the upper vessel and the spout, the pressure. exerted. on the strainer by reason of the existence of vacuum in the lower vessel is such that the margin of, the strainer is flexed sufficiently to. shift the coffee grounds from. their clogging; or blocking position. Such. action takes place automatically and may occur at any time, to. varying extents, depending upon the amountof blockage.

It is. a further object of my invention to provide a strainer at least a portion of which is formed of a flexible resilient elastic material and able; to. withstand hard. usage without damage. Some. of the strainers or filters currently in use are formed of. porcelain. or glass and are easily damaged.

It. is yet another advantage of my invention that the means for retaining the strainer in position is simple but effective, and may beeasily manipulated from that, side of the strainer at which the ground coffee. is disposed.

Another advantage of the strainer of my inventionis that it may be easily cleanedv and sterilized' and used for long periods of time. forms of strainers presently on the market must Many 3 be discarded after a short period of use, sometimes after a single use.

Although the strainer is particularly well adapted for use in a so-called pressure coffee maker, such as that just referred to, it is adapted for use in other devices of a like nature and may also be employed even when pressure is not so produced in the system to be filtered. In such instances the filter may be flexed by hand or by some mechanical implement.

Other objects, uses and advantages of my invention will become apparent from the following description when taken with the accompanying drawings in which:

Figure 1 is a vertical sectional view, with portions being shown in elevation, of the strainer of my invention disposed in a pressure coffee maker;

Figure 2 is a vertical sectional view of the strainer of Figure 1, the section being on a plane at a 90 an le from that of Figure 1 and showing onlv the strainer;

Figure 3 is a plan view of the device of Figures 1 and 2 looking in the direction of the arrows 33 of Figure 1;

Figure 4 shows the strainer of my invention with a modified form of retaining means;

Fi ure 5 shows a strainer of modified form which is adapted to cooperate with a coffee maker having grooves disposed in the upper vessel at the entrance to the spout:

Figure 6 shows a modified form of strainer of my invention having guide means for locating the strainer in its o erating position;

Fi ure 7 is a plan view looking in the direction of the arrows '!'I of Figure 6: and

Figure 8 is a view of yet another modified form of strainer.

Referring now to Figures 1, 2 and 3 of the drawin s there will be seen a pressure coffee maker, indicated generally by the reference numeral It. com rising, in the main, a coffee fiagon or urn I2, which is the lower vessel of the two vertically aligned vessels; a bowl I4 which is the upper vessel in which round coffee is disposed: and a strainer I6 which is dis osed in the bowl I4 on a sup orting wall or surface I5 about the entrance to the down snout or funnel I1, which spo t evtends throu h a gasket I8 in the neck or thro t of the urn I2 and into t e lower portion of the u n to a posit on sli htly above its bottom wall 22. lhe urn I2 and bowl I4 may be ma le of lass, metal or other suitable materials or co binations of materials. The gasket I8 is usual y carried a out the s out at its uppermost p rtion and. is ada ted to fit ithin the neck 20 of the urn I2 in order to provide an air tight fit between the neck and snout. Around the neck 20 is positioned a gasket 2| in a peri heral groove of which a clam ing ring 23 which is adapted to be connected with a handle (not shown).

The pur ose of the strainer I6 is to ermit the passage of fluids between the s out I 'I and the bowl or upper vessel I4 without permitting ground coffee or other solid matter to pass from the bowl portion to the s out. The oneration of the strainer will be set forth more fully hereinafter.

The filter I5 comprises a generally bell-shaped member having a central body portion 24 which is domed and a downwardly and outwardly extending margin 26 the under surface of which mar in has a plurality of generally radially extendin grooves 28. The strainer IS in its referred form is composed of a flexible, resilient elastic material, such as rubber or similar plastics, although it is possible to have the central body portion 24 of a material which is not flexible or resilient, so long as the margin in such strainer is elastic, flexible and resilient. Integrally formed with the strainer I6 and extending downwardly from the central body portion 24 is a tongue 30 which is adapted to provide a means for connecting to the strainer a coiled spring 32, the upper end of said spring passing through a hole or aperture 34 in the tongue 30. The lower end of the spring 32 is connected with a hook or connecting member 36, said hook, in the preferred form, being formed of wire and having one leg which extends upwardly through the coiled spring 32 and through a passageway 38 in the central dome shaped portion 24 of the strainer I5. It will be understood that the hook could be connected with a rod, comparable to the wire 31, and that the rod could then pass through the passageway 38 in the strainer I 6 to a position on the upper side of said strainer. As shown, the hook 33 and wire 3'! are integral and the wire at its upper end provides a loop 39 which may be engaged by a finger, or fingers, of the user. There will also be seen a resilient guide means 49 for the hook 35 which guide means serves to urge the hook 36 against the inner wall of the down spout I! so that the user will have no difficulty, when inserting the hook and spring in the spout, in engaging the hook 36 over the lower end of the spout II.

In order more easily to describe the operation of the strainer, the procedure for making the coffee in the illustrated pressure coffee maker ID will be briefly set forth. With the upper and lower vessels I4 and I2, respectively, separated, water will be placed in the urn, or lower vessel, I2 to a level somewhat below the neck 29. The user will then take the strainer IS in one hand and the bowl, or upper vessel, I4 in the other hand and insert the book 36 and spring 32 in the spout I1 of said vessel. When the strainer I6 is disposed on the supporting surface or bottom wall I5 of the bowl I4 about the entrance to the spout H, the user will then depress the wire or rod 31 by means of the looped portion 32-! against the action of the spring 32 with the result that the hook 36 will travel to the end of the spout I I. The guide member for the book 36 will cause it to engage the inner side wall of the spout I'l until it reaches the lower end of said spout, whereupon the resilient guide means 40 will cause the hook 36 to snap outwardly and over the lower end of the spout. Then when the user releases the pressure on the wire or rod 31 the hook 36 will move upwardly and enga e the end of the spout so that the strainer will be resiliently retained on the suporting surface I5 of bowl I4. Coffee in ground form is then placed in the bowl I4 around the filter IS in sufficient quantitv to make an appropriate amount of coffee of desired strength and the bowl I4, with the gasket I8 surroundin the upper portion of the spout I1, is then inserted through the neck 20 of the lower vessel or urn I2, until an air tight fit of the asket relative to the spout and the neck is obtained.

The coffee maker I0 is then taken by its handie and set over a source of heat in order to cause the water in the urn I2 to boil. At this time it will be observed that the only outlet from inside the urn I2 to atmosphere is throu h the spout I1 the lower end of which is submer ed in the water which is boilingin the urn. Conseaesarir quently; as. boiling commences, pressure develops within the. urn l2; and acts: upon. the; surface. of the. water to. force; it: downwardly in. the um. and upwardly through the spout: IT and through the roovesv 28 in the: strainer t8: and thence to. the ground coffee in. the bowl H. The. bowl [-4. is of such capacity that it. will accommodate all. of the water which may be forced upwardly through the spout: 1.1.. When the. level of the boiling water in the. urn i2 is below the lower end of. spout IT, water will. no longer be. forced up: the spout but instead vapor at. greater than atmospheric pressure. will rise up. the spout; and pass: through the strainer and liquid. which is. now' in. the. upper vessel or bowl [4. When the hot water passes through the strainer to the ground coffee a coffee infusion results. At such time as the water in the urn has reached a level just, below the spout ["1 the coffee maker may be removed from the source: of heat to permit the urn t2 and its contents: to cool. The cooling. causes a contraction of the gases or vapors within the. urn l2 and a vacuum thereby results. Air pressure then acts on the surface of the coffee infusion in the bowl l4. and causes it to run down the spout i! into the urn l2. As the liquid passes from the bowl M to its spout l-T the ground coffee and other solid matter is strained by the strainer 16.

If, at this time, the strainer becomes clogged for any reason the existence of vacuum in the urn l2 and the consequent pressure tending to force the liquid in the bowl 14' into the urn l2 will act on the strainer 16 to cause the flexible resilient elastic margin to be flexed a slight amount. The very slight flexing of the margin which contains the grooves 28- will break the clogging action so that the coffee infusion will continue to pass through the strainer and down the spout ll into the urn I2. As will be readily understood the strainer l6 remains positioned on the supporting surface: about the entrance to spout I-l during passage of the liquid either upwardly or downwardly by reason. of. the resilient biasing means 3-2 and hook 36.,

When all of the. liquid in the upper vessel or bowl I4 has run into. the urn l2, the upper vessel M is removed, along with the gasket l8, from the lower vessel and the lower vessel then serves as an urnor fla on for directly serving the coffee.

Thev coffee grounds inthe bowl [4 may then be removed therefrom and the strainer may be removed for cleaning and for stora e by depressing the rod or wire 3! by the loop 39 and manipulating it sidewavs sufficiently to disen age the hook 36 from the lower end of the spout l1, whereupon the hook, spring and strainer may be released from the spout l1 and bowl H.

In Figure 4 there is shown a modified means for retaining the strainer 16 upon the supporting surface 15 in the bowl l4, said means comprising a chain 31 connected to the ton ue of the strainer with a weight 33 connected at the lower end of the chain. The dimensions of the weight are such that it must be rotated from its free han ing position to have its longer axis parallel to the axis of the spout I! of bowl l4 before the weight can be passed through said spout to release the strainer Hi from the bowl. This modification serves to illustrate that more than one means may be employed for seating the strainer within the bowl l4 about the entrance to the spout IT. The loop 39 associated with the strainer 16 is employed for more easily manipulating the same.

Although the passageways 28 in the strainer t6 are shown inthev form of grooves in. the; underside of the-margin 2-6. in the; devices of Figures I through 4; it will: be; appreciated that: in place of the. grooves: there may bev employed circular passageways, or passageways. of other cross-sec.- tional shape or outline, which are. not open on their undersides but instead pass radially inwardly from theouter edge. of the margin 26 toward the central axis of the strainer. Furthermore, if desired, circular passageways through the margin could be located at. a higher level, that is, nearer thev central body portion and. might even be disposed in the. central body portion it.- self. Preferably, however, the passageways. in the strainer should be, in the. margin and, should be formed a groovesso that the passageways are defined by the grooves. and the. adjacent support ing surface comprising the bottom wall I 5 of the bowl M.

Referring to Figure 5 of the drawings there will be seen a strainer IBA which is, bell shaped and which isemployed in inverted form and has its smooth exterior wall resting over grooves 29 which are formed in the vessel [4 at. the entrance to the spout ll. Fluid is adapted to pass through the grooves 29 in the vessel M from the bowl to the; spout or vice versa. If clogging should occur around the periphery of the strainer at the grooves 29, pressure on the strainer [6A in a direction toward the lower vessel (not shown) will cause the flexible resilient margin 29 to flex suihciently to break the clogging action of. any solid matter such as coffee grains which have accumulated and blocked the flow of liquid to the grooves 29. Resilient retaining means such as that illustrated in Figures 1 and 2 is employed for maintaining the strainer ISA in position about the entrance to the spout 51, said resilient means being connected with a tongue 30A which extends downwardly from the domed central body portion 24 of the strainer 16A. The resilient retaining means may be manipulated in the same. fashion as that described above with respect to the. device of Figures 1 and 2.

The modified form of strainer illustrated in Figures 6 and 7 is similar in most respects to the strainer illustrated in Figures 1, 2 and 3 except that in place of the tongue 30 of the devices of Figures 1, 2 and 3 there is employed a tapered guide, cross-shaped in cross section, which serves not only as a means for connecting the strainer 16 with the. resilient: retaining means but also as a guide for centering the strainer It with respect to the spout of the upper vessel M. The wire 3;! and its loop 39 are adapted to manipulate the resilient retaining means in the same fashion as described above with respect to Figures 1 and 2-.

In Figure 8 is shown a modified form of strainer t6 which is generally flatter and less bell shaped than, the devices described above and has a central body portion 24 and flexible resilient margin 26' with a plurality of grooves 28 extending radially' from the outer edge of. the margin toward the central axisof the strainer. From this model" fled form of the invention it will be seen that the essential characteristic of the strainer is its flex-- ibleresilient margin which may be flexed when pressure is applied to the strainer.. The flexing action of the margin, particularly at its outer edge, is readily achieved by having the central body portion somewhat domed or ached, and with the margin outwardly turned since pressure at the central body portion will then tend to direct the margin radially outwardly and turn its outer edge up a slight amount. As the rate of flow through the strainer is varied by the tendency of the coffee grounds to cause a blocking action, variations in pressure on the strainer are produced so that there may be a slight flexing action going on throughout the entire period when the coffee infusion is running from the upper vessel into the lower vessel. Such action is automatic and therefore provides a strainer which is selfclearing.

It will be observed that the various forms of strainer illustrated and described above are all made of a flexible, resilient elastic material which is impervious to liquids but it will be understood that it is sufficient if the margin alone is elastic, flexible and resilient. The fact that the central body portion of each of the forms of strainer illustrated and described above is of greater cross section than the margin is for the purpose of maintaining the shape of the strainer and preventing it from becoming inverted due to pressure. It will be readily understood that if the central body portion is not itself flexible and resilient but is, instead, substantially rigid, or if it is made of a different type of flexible resilient material, the thickness of the central body portion could be modified.

Although I have illustrated and described preferred embodiments of my invention it will be appreciated that variations may be made therein by those skilled in the art, in view of my disclosure, and, consequently, I do not intend to be limited to the preferred forms except as the appended claims are so limited.

I claim:

1. A strainer for a vacuum type coffee maker having a bowl with a depending axial spout comprising an imperforate dome shaped body thicker at the center than at its margin, said body having a concave undersurface terminating in a margin provided with outwardly extending channel-like passages, said body being formed of an elastic material whereby the flexibility and resiliency increase along the radius of the body, said body in response to vacuum pressure exerted on its underside changing its shape to increase its peripheral dimension at the margin thereby to change the shape of said passages to prevent clogging of said strainer.

2. The strainer of claim 1 wherein the elastic margin of the strainer is grooved on the side which is disposed against the supporting surface with the grooves being of a size to permit the passage cf fluids therethrough and to strain out solid matter.

3. The strainer of claim 1 wherein the strainer is an integral domed elastic member thicker at its central body portion than at its margin.

4. A vacuum type coffee maker strainer adapted to be disposed on a generally flat supporting surface at the entrance to a passageway, said strainer comprising an integral member having an imperforate generally rigid central body portion and a flexible resilient margin of decreasing thickness provided with passageways on the underside extending inwardly from the periphery of said margin, said margin changing the shape of said passageways in response to vacuum pressure exerted on the body portions and a resilient means adapted to seat and to retain said flexible resilient margin against said supporting surface.

5. A vacuum type coffee maker strainer adapted to be disposed on a generally flat supporting surface about the entrance to a passageway, said strainer comprising an imperforate member having a central body portion and a flexible resilient elastic margin, said margin having passageways therethrough from the edge to the under surface, said margin being adapted to engage said supporting surface about the entrance to said passageway and being adapted to move radially thereover in response to pressure exerted on the strainer toward the supporting surface during the straining action when clogging of the strainer occurs, such radial movement thereby automatically overcoming the clogged condition by changing the shape of said passageways.

6. A vacuum type coffee maker strainer adapted to be disposed on a generally flat supporting surface of a bowl about the entrance to a passageway, said strainer comprising a member having a central imperforate body portion and a flexible resilient elastic margin, said margin being grooved on the side which is disposed against the supporting surface with the grooves being of a size to permit the passage of fluids therethrough and to strain out solid matter, said margin being adapted to move radially over said supporting surface in response to pressure exerted on the strainer toward the supporting surface during the straining action when clogging of the strainer occurs, such radial movement thereby automatically overcoming the clogged condition by changing the shape of said grooves.

7. The strainer mechanism for a vacuum type coffee maker which includes a bowl having a generally flat supporting surface about the entrance to 9, depending spout, said strainer mechanism comprising an integral member having an imperforate central body portion and a flexible resilient elastic margin, said elastic margin being provided with channel passageways adapted to permit the passage of fluids and to strain out solid matter, said margin being adapted to engage said supporting surface about the entrance to the spout and being adapted to move radially thereover in response to pressure exerted on the strainer toward the supporting surface during the straining action when clogging of the strainer would occur, such radial movement thereby automatically overcoming the clogging action.

FREDERICK W. STORNER.

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